text:
There is a difference in the runway lighting systems symbolized in the planview and the lighting system specified in additional runway information?
Although two different lighting systems are symbolized for two runways in the airport plan view, the same lighting system is specified for runways 05 and 23 in the additional runway information section. Why? I am sharing the picture of Jeppesen symbols and the airport plan view below.

I'm not a pilot, so maybe I'm totally misreading what you've shown, but in your 2nd image, it appears to me that the symbols for Rwy23 and Rwy05 are distinctly different and are labeled differently (SSALS vs HIALS). Can you clarify what you mean?

Although they have different lighting systems, the common "HIALS" expression is used for both runways in the additional runway information section at the bottom of the chart.

This question is more clear than the other one, and answers itself.

HIALS stand for High Intensity Approach Lighting System.  (as opposed to MIALS for Medium Intensity...)
HIALS is a broad category of different approach lighting configurations, (all high intensity) but doesn't itself describe more detail like the specific number of light bars, spacing, etc.
As your second illustration clearly shows, a HIALS system could be configured as a Calvert, Calvert II, or even a SSALS, which stands for Simplified Short Approach Lighting System.  (presumably of high intensity...)
In other words, Calvert, Calvert II, SSALS and others are specific configurations, or arrangements of lighting within the category HIALS.

Thank you, sir.


text:
Why is the distance between BRY VOR and missed approach point 0.2 DME in the plan view, while it is specified as 0.1 DME below?
Why is the distance between BRY VOR and missed approach point 0.2 DME in the plan view, while it is specified as 0.1 DME below? If we consider that the localizer is 0.2 DME ahead of the runway threshold, the IYEN D0.7 information is correct. But in the plan view, the missed approach point seems 0.2 DME away from BRY VOR, not 0.1. Why is this difference due? I showed it with red marks in the picture. Also, this picture is from the ILS Z or LOC Z Rwy 25R Jeppesen chart of LTBR airport page 11-1.

This might be a mistake in the chart.
The Introduction to Jeppesen Navigation Charts defines the number between two navaids/fixes as follows:

10 — Nautical Mile (NM) distance between two navaids and or fixes.

I looked up the exact coordinates of the relevant fixes in my AIRAC 2210 database:

Name
Latitude
Longitude

BRY (YENISEHIR VOR/DME)
40.262527778
29.594027778

BRY (YENISEHIR NDB)
40.262527778
29.594027778

MA25
40.261908333
29.591111111

MA25R
40.271713889
29.635888889

As you can see, the VOR/DME and NDB are co-located. The MA25R point is not part of ILS or LOC approach (it is used on the VOR Z approach). If you calculate the distance from the VOR to the MA25 fix, which is the missed approach point for the LOC approach, you get:
$$ \text{distance}(\text{BRY} \rightarrow \text{MA25}) \approx 0.1387 \, \text{NM} $$
So it should really say 0.1 there. Just for reference, the distance to MA25R is close to 0.2:
$$ \text{distance}(\text{BRY} \rightarrow \text{MA25R}) \approx 1.9950 \, \text{NM} $$
But this is in the other direction of the VOR.

In general, the DME distance can be larger than the coordinate distance because the DME shows slant range. If you look to the right of the VOR on your chart, you see a distance of 2.2 NM to a point at DME 2.3 to BRY. This could be due to slant range.

The distance to the runway threshold of 0.5 NM is also consistent with DME 0.7 to the ILS DME, if that DME is located near the aiming point, which is about 380 m (~0.21 NM) away from the threshold:

(Google Maps)

@757toga But how can the slant range be less than the lateral distance?

Agree with @Bianfable -- slant range being the discrepancy would cause the numbers to mismatch in the other direction... the slant range (DME reading) should be larger than the lateral distance, not smaller.

Unless it's a matter of how rounding is handled... when the exact lateral distance is 0.13 NM, which becomes some slant range, they may round that down so that the pilot starts the missed approach early rather than late. But to make all the lateral distances sum up correctly, perhaps the designer had a reason to round the 0.13 up to 0.2 instead of the usual convention. Or it's simply an error.

Many thanks to everyone for their valuable replies and comments. I will assume that the DME values in the Approach profile are the slant range and the distance given in the table below is the lateral distance. But I will not forget the possibility of inaccuracy or rounding calculation.

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text:
Which one is racetrack? Isn't it a holding over VOR on the left and holding over FIX on the right?
Which one is a racetrack? Isn't it a holding over VOR on the left and holding over FIX on the right? If one of them is a racetrack, how is it different from holding? Or are they both used in the same way on this chart? Because MHA is given for both symbols, so it is certain that they are holdings, isn't it? In addition, one symbol is thick and the other is a thin line. This picture is taken from page 11-2 of the LTBR Jeppesen chart (ILS Y or LOC Y Rwy 25R).

The BOLD hold at KESEV is the required course reversal prior to the final approach. The lighter line hold at BRY is part of the missed approach -- after the procedure has been attempted unsuccessfully.

I believe they didn’t disambiguate between the two in comment (3) because it doesn’t matter, 230 is the published max for both.
Both are holds, and both could be called “racetracks”…  The reason for the bold line is that KESEV hold is an expected, integral part of the approach procedure.  There are legal/procedural differences that occur once established on a published approach segment, and the bold line denotes that the KESEV hold is an approach segment.

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text:
How are Rolls-Royce engines different to others?
I heard that Rolls-Royce engines has 3 engine spools.
Are they different in design compared with GE, PW engines?
thanks

For RR Trent XWB engine for a350, is there any difference in specific to spool design?

Yes, RR engines typically have 3 spools while GE and P&W generally have 2.  There are several design tradeoffs.  Briefly:
3 spools are easier for the aerodynamic design. For example, compressor stall can happen when the front stages of the compressor are pumping more air than the back stages are able to accept.  On a 2 spool machine, the front and back stages are all on the same shaft going the same speed.  However, on a 3 spool machine, the front and back stages are on different shafts.  So one shaft can speed up or slow down to better match the stages.  To work around this issue, 2 spool machine usually need to have more variable geometry (such as variable stator vanes) than 3 spool machines.
2 spools are easier for the mechanical design.  Every spool needs to be supported by bearings.  More spools means more bearings.  Bearings have to be supported by frames and cases.  More bearings means more frames (or more complicated frames).  Every spool has critical speeds. So more rotors means more possible critical speed issues.
There is not a clear winner.  2 spools are better for some things but 3 spools are better for the other.  Each company is going to tell you that theirs is "the best", but really they are about even overall.

I heard that Rolls-Royce engines has 3 engine spools.

According to Rolls Royce

The Trent family's unique 3 shaft design makes every Trent engine shorter, stiffer, lighter and more FOD (Foreign Object Damage) resistant than its equivalent 2 shaft engine. This results in significantly less performance deterioration and delivers an additional fuel burn benefit of 1% through life.

(my emphasis).
The implication is that none of the Trent's major competitors use a three-shaft design.

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text:
What are the meanings of the phrases DAY, RWYCC, 6/6/6 in ATIS?
What are the meanings of the phrases DAY, RWYCC, 6/6/6 in ATIS? I marked the section after QNH in yellow.

RWYCC 6/6/6 means "Runway Condition Codes" of 6 (dry) for the first, middle, and last third of the runway.
RCC's, as they're also known, are a relatively new way to report the state of the runway surface, and range from 6 = dry to 0 = nil braking. The FAA published this document with further explanations. They're reported in that format of three separated values; the most common are 6/6/6 (i.e. runway is dry) and 5/5/5 (i.e. runway is wet but good braking). Lower values are generally seen only with snow/ice or heavy rain + standing water. The convention allows for reports differentiating the condition of different areas of the runway, such as 5/5/1 (last third has "poor" braking action), but that seems to be rarely used.
One might assume that "DAY" is simply reporting that it is daylight there, but without context (where is this report from?) that's all I can offer; that isn't a report used in ATIS broadcasts that I've seen.


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What are the names by which runways are classified according to the configuration of the placement of the approach lighting systems?
What are the names by which runways are classified according to the configuration of the placement of the approach lighting systems? (I'm not talking about HIALS or HIALS-II because those terms are used for so many configurations)

In the Airport diagram, we see that the approach light systems for the two runways are represented by different symbols. The reason why these symbols are different is that the placement and configurations of the lighting systems are different. So what are the names of these different configurations? That's what I was asking.

Here's the reference material for US airports.  I suspect from your airport diagram that you may not be referring to US:
Figure from the US AIM (Aeronautical Information Manual), located online here.

Figure from the FAA Digital Terminal Procedures Supplemental

From the Chart Supplement Legend

Thank you for your answer but I need to ask that to be sure about it, ALSF is the equivalent of HIALS and ALSF-II is the equivalent of HIALS-II? Am I right about that?

In the US I haven't seen a reference to "HAILS-II" so I am not sure.  The FAA breaks approach lighting systems in "High Intensity Approach Lighting Systems" and "Medium Intensity Approach Lighting Systems."  ALSF-2, ALSF-1, SSALR, SALS and SALSR are all considered "High Intensity" systems.  MALS, MALSF, MALSR, SSALS, and SSALF are all medium intensity.

The ICAO system in Europe is trying to copy from the US FAA, but unfortunately many things are missing. Thank you very much for your answers.


text:
What exactly is the difference between RA, SHRA and TSRA in METAR and TAF reports?
What exactly is the difference between RA, SHRA and TSRA in METAR and TAF reports? I couldn't find a source where they were all compared together.

Short answer:

RA: Moderate rain
TSRA: Thunderstorm with rain
SHRA: Shower(s) of rain

How this is constructed is detailed below.

From WMO Aerodrome Reports and Forecasts, abbreviations for precipitations are:

A type of precipitation is RA for rain. It can be associated with a one or more qualifiers, e.g. TS for thunderstorm, SH for shower, + for heavy, etc. No qualifier means moderate.
Definitions

Thunderstorms: One or more sudden electrical discharges, manifested by a flash of light (lightning) and a sharp or rumbling sound (thunder). Thunderstorms are associated with convective clouds (cumulonimbus) and are usually accompanied by precipitation. The associated cumulonimbus has vertical updraughts that may reach 30 m/s in the more vigorous cells. Downdraughts also occur,
especially in the later stages of development, with speeds of about half of those for updraughts.

Showers: Precipitation, often short-lived and heavy, falling from convective clouds. A shower is characterized by the suddenness with which it starts and stops, and generally by large and rapid changes in precipitation intensity.

Use

The qualifier TS shall be used whenever thunder is heard or lightning detected at the aerodrome within the 10-min period preceding the observation.

When an automatic observing system is used and when showers (SH) cannot be determined with a method that takes account of the presence of convective cloud, the precipitation should not be characterized by SH.

The descriptor SH (showers) cannot be associated with ice pellets (PL).

Examples

RA: (Moderate) rain
+SHRA: Heavy showers of rain
TSRA: Thunderstorm with rain

Note that TS can be used with other precip, for example TSSN, or with no precip, as VC TS. Note also that the intensity modifier applies to the precip, so +TSRA means "thunderstorm with heavy rain" and NOT "heavy thunderstorm with rain."

@randomhead: One or two qualifiers can be used with any single weather phenomenon (SH, +, ... are qualifiers, not weather phenomena). Generally, qualifiers cannot be used alone, but TS is an exception, it is both a qualifier and a phenomenon (though this is not visible in the table).

TS stands for thunderstorms, so TSRA means rain associated with thunderstorms.
RA means steady and continuous rain. SHRA means rain showers. Showers stop and start abruptly and can vary in intensity.


text:
Is ACARS OOOI format standard & unified?
Are ACARS OOOI messages standard between all system manufacturers and service providers like ARINC and SITA ??


text:
How impactful is De-icing on flight margins?
A quick google search suggests that deicing is a very expensive activity, with many suggesting it might be 5-10k for both deicing and anti-icing fluid.
Given that flight costs typically are lower for customers in the coldest months of the year (in North America), how destructive is deicing on flight margins?
I can’t help but imagine that in the colder parts of the country flying regional jets or Dash-8s, the cost of deicing could consume a large portion of the total revenue realized of the flight. This isn’t explored in public financials issued by airlines, it’s often bundled in with other operational costs such as in Air Canada’s annual report.

I think it only makes sense for airlines to annualize the cost of de-icing and factor it into the price of each ticket throughout the year and its overall profit margin per flight. Hence, you don't see it as its own line item on annual reports. It is part of the overall cost of operations and budgeted for ahead of time. Remember that the major airlines' de-icing cost is a year-round expense. When they're not paying for de-icing in the northern hemisphere, they are paying for it in the southern hemisphere, and vice versa.
Moreover, major airlines may operate their own de-icing crews at their main hubs. Meaning they can purchase de-icing fluids at wholesale or volume-discounted prices. They can then sell these services to private jets, charter operators, or other airlines. Likewise, they can trade the service with their alliance airlines. So, for example, American Airlines might provide de-icing services for British Airways at JFK in exchange for de-icing services at Heathrow. All of this can help offset some of the cost of de-icing.
What would be interesting to see are the annual reports of an airline that operated only in warm climates and then expanded its network into cold temperatures and see how much its operating costs have gone up; of course, the increase wouldn't be only de-icing.


text:
Tracking ATC communication with a flight of interest
I am a complete newbie, but hopefully this question makes sense. I am interested in tracking communication between a flight and ATC. I've found www.liveatc.net, but I have difficulties understanding what code to use. When the flight was on the ground, I used the code of the origin airport. I could listen them talk to the flight of interest. Then they moved to Germany, where live ATC data is not available. Now they are over Poland, but I don't know what code to look for. Probably they don't talk to any particular airport tower but to something responsible for a big part of the country? Is there some way to convert for example, the current flight location (GPS) to a code to type into LiveATC?

A lot of European countries make it illegal to listen to radio communications, so they may not be available publicly.

But even when they are, you’d need to listen carefully to the whole flight and follow the handoffs.  Once you lose it you’d be very lucky to find it again until nearing its destination.

There are a lot of things in play based on the altitude of the aircraft for which radio zone they are talking to. I can only imagine this is more complicated in Europe where radio could travel farther than country borders.
Your ability to do this will improve as you gain experience. Try to search out High and Low IFR maps because those will have documentation on the frequencies used for routes. Whether you can use that information legally I'm not qualified to answer. Maps dealing With VFR are more verbose and often contain additional information meant for human pilots.
The best way is to catch the handoff from one zone to another, record information and then try to relate it to the maps You have available.
Good luck! It wouldn't be as fun if it were easy.

Yes, you will need to use IFR charts to identify the sector the flight is currently in. You can also use Flight Aware to get the filed flight plan and Sky Vector to map it to help better identify the ATC sector.
But honesty majority of ATC communication happens around the airport environment. There is very little chatter en route, it is mainly handoff from one ATC sector to the next. Not sure about EU but in the US there aren't many center/radar frequencies being broadcasted to LiveATC, mostly airport frequencies only.

The reason is mostly technical. Centers have antennas on really tall places to extend their viable horizon and they are talking with aircraft over FL180. To cover a center adequately for all of the communications you would need a receiver closeish to their transmitter and 5-6 receivers around 60% the radius of their Artificial Horizon to properly pick up most of that traffic. Also just like large airports' center frequencies are different depending on where you are coming and going to if you are transitioning from center to center.


text:
What are the four shades of grey on the FR24 map?
I just noticed the sunset border on Flightradar24 maps. I wonder: what are the 4 shades of grey, and why are they relevant? Why not just show one?

I'd like to point out that a question called "3 stages of twilight" is inherently different from "four shades of grey on the FR24 map". First, because I need to know there are stages of twilight and, second, because I need to know that FlightRadar shows the stages of twilight. Then I can find that question and get the information I need. So, instead of calling this question a duplicate, it might have been more relevant to answer "these are the twilight stages" and point to the other question. As WPNSGuy did.

Varying levels of daylight, going into night.
This previous question goes into much more detail, and it may indeed be related to the aeronautical definitions as day turns into night.
What are these 3 stages of twilight?

Upvote for being correct, but there might be a deeper meaning...  For example, there is sunset, nautical twilight, etc. that have distinct meanings.  Could it be related to these definitions?  I don't have time or motivation to research, just throwing it out there...  ;)

@Michael Hall - Looking through the FR24 glossary and FAQ, and searching for "day", "night", "grey", "gray", I see nothing related to the varying shades of grey. Of course, I may be just missing it.


text:
United’s 787-9 upgrade
I read this article about United increasing their performance of the 787-9. More specifically increasing thrust and range, But it says this will be done over software. How do you make an engine burn less fuel and more thrust over just software.
article

Yes it does, Thanks

Complex Control
There are a non-trivial number of actuators in a modern jet engine. In addition to the throttle, there are valves which control bleed air at different stages of the engine, stator vanes can be rotated to compensate for airflow rotation speeds between stages, and different parts of the engine are actively cooled by air jets to minimize the gap between the end of the turbine blades and the casing of the engine (the engine will expand under heat and let more air pass around the blades if not actively managed).
All of these factors affect fuel efficiency under different conditions, and it is virtually impossible to build an algorithm by hand which will produce the optimal values under all conditions. Usually, a software model will be built, optimized and validated for the most common regions of the input parameter space, and tested to ensure that performance remains reasonable in the more extreme portions. But this often leaves many conditions in which the algorithm is known not to offer optimal control. One of the reasons machine learning is becoming so popular is that it can automatically optimize these high-dimensional problems (look at all the sensor inputs and think about how to control each valve and actuator). Even then, a solution discovered by ML is not guaranteed to be optimal either, leaving room for future improvement.
Iterative Improvement
Rather than trying to craft the perfect algorithm in one go, all complex software starts at a simpler stage and evolves over time. One of the hardest constraints is testing. While there are theoretical models of how an engine behaves under a variety of conditions (ambient pressure, temperature, humidity, etc.), a real-world engine will deviate from this model due to manufacturing variance up to model inadequacy. So if you produce a new control model and claim that it improves engine efficiency by 3% under long-range cruise conditions, then at some point, you need to actually fly a route and gather some data. Such tests could have been done at any time, including before the FADEC was originally released to production. But waiting until you have optimized every scenario as much as you can is a significant opportunity cost that most corporations cannot afford. Much better to release a product that is at least as good as the current market (or some defined improvement level), and then iterate the design after you are already rolling engines off the assembly line.
This is why software updates are constantly being released, in pretty much every area of software production. Imagine if Tesla refused to sell any cars until Full Self-Driving was totally finished. In general, you should assume that any control system which has more than a dozen parameters also has a complex optimization space that is non-trivial to characterize completely. The FADEC illustrated in the link above has half a dozen actuators and 10 input parameters. That means the optimal control program is at least a 6-dimensional surface within a 16-dimensional parameter space. It is not hard to imagine that the first approximation of this program leaves a lot of room for improvement, even if the performance is better than all previous designs.

This is not at all uncommon in car engines, and optimization can be done in jet engines also.
For longevity and safety reasons engines are not ran to their full capacity (except in drag race cars), there is always some margin, and in aircraft engines this margin is considerable.
As engine models "mature", more data is availlable about how they stand the test of time. With this data the algorithms running the engines can be optimized, possibly leading to performance  gains.

In piston engines, you can control ignition timing, valve timing, mixture ratio etc. But how do you control anything on a turbine engine? Isn't the fuel flow through the nozzles the only thing that can be controlled on a turbine? (Except perhaps such miscellaneous items as VIGV's or the idle RPM of the engine - so is that what they optimised?)

@AdityaSharma I don't know what they actually did, but based on reading the linked article it sounds like they only increased max. TO thrust (by allowing higher fuel flow in software). This will then allow you to takeoff with higher weight, i.e. more fuel, therefore increasing range.

@Bianfable Sounds reasonable, thank you!

It will also enable quicker ascend to cruise levels, should one be granted such profile.

It means that software revisions to the FADEC code have improved the precision of the FADEC and its ability to manage temperatures when regulating fuel flow.
This means they are able to shave off more of the tolerance margins, fudge factors you could say, built into the code and can run the engine ever closer to its actual thermodynamic limits without risk of exceedances.


text:
Are spoilers primary or secondary flight control surfaces?
The literature on primary and secondary flight controls is very contradictory.
My professor provided this image from which I infer that spoilers are used for primary flight control:

Also, here it says that spoilers qualify as primary flight control.
On the other hand, Skybrary lists spoilers as secondary flight controls.
What kind of flight controls are spoilers?

It really depends on the aircraft: on the first versions of the B-52 for example, spoilers were the primary and only control surface.

There does not seem to be a consistent definition for primary and secondary flight controls. It depends on the aircraft.
The Airbus A310 FCOM distinguishes between primary and secondary controls as follows:

The primary flight controls ensure flight path control and include:

pitch control, using:

the elevators, which are hinged to the Trimmable Horizontal Stabilizer (THS), and
the Trimmable Horizontal Stabilizer (THS) which provides Pitch Trim.

roll control, using:

1 aileron per wing, and
the 5 outboard spoilers (Nos. 3 to 7) on each upper wing surface, as roll spoilers.

yaw control, using a single rudder.

[...] The secondary flight controls are lift and drag augmenting devices and
includes:

flaps: there are one double slotted inboard flap and on single slotted outboard flap.
slats: there are three slat sections per wing (inner, center and outer). Associated with the slats a Kruger flap is located on the
leading edge of each wing, inboard of the inner slat section.
spoilers: there are 7 spoilers (Nos. 1 to 7) on each upper wing surface which are used as speed brakes, roll spoilers or ground
spoilers for lift dumping (all 7 surfaces).

(emphasis mine)
Therefore, spoilers can be counted as primary controls, but only those which are actually used as roll spoilers (asymmetric deployment in the air).
As far as I could find, Airbus does not distinguish between primary and secondary controls in subsequent models.

The Boeing 747 FCOM (-400 and -8 models) defines the primary and secondary controls as follows:

The primary flight controls are elevators, ailerons, and rudders. [...]
Secondary flight controls include a moveable horizontal stabilizer, spoilers, and
leading and trailing edge flaps.

(emphasis mine)
Here, spoilers are clearly excluded from the primary flight controls. Other Boeing FCOMs I found define the primary flight controls in a similar way, but do not go into further details about secondary flight controls.

It depends on the aircraft.  For example:

On a Learjet 45 airplane. There are spoilers that are mainly used in the air to slow down and/or descend.  However, when flaps are increased, those same spoilers become spoilerons and help the airplane roll.  There is even a roll disconnect feature that will disconnect the pilot side yoke to the aileron cables and solely use the spoilerons to roll the aircraft.

To summarize I would say this

Spoilers are secondary flight controls.  In the air, the help the airplane slow down and/or descend.  On the ground, they are used to spoil lift and transfer the weight of the airplane to the wheels to aid in braking

Spoilerons are primary flight controls.  They help the pilot maintain roll authority by either supplementing the ailerons or being the only way to roll the airplane.


text:
Just how do the underbanking and overbanking tendencies work?
I understand that most GA airplanes and gliders exhibit an underbanking tendency at low bank angles and an overbanking tendency at high bank angles.
According to the Airplane Flying Handbook, chapter 3, page 3-11, if the aircraft is in steady, coordinated flight at a bank angle less than about 20 degrees, then

This shallow bank is such that the inherent lateral stability of the airplane slowly levels the wings unless aileron pressure in the desired direction of bank is held by the pilot to maintain the bank angle.

On the other hand, if the aircraft is in steady, coordinated flight at a bank angle greater than about 45 degrees, then

The  airplane  continues  in the direction of the bank even with neutral flight controls  unless  the  pilot  provides  opposite  flight  control aileron pressure to prevent the airplane from overbanking.

What causes these underbanking and overbanking tendencies, exactly? How do they work?
I know that when an aircraft is in a coordinated turn, the situation as experienced by the aircraft is almost identical to straight flight. As far as I know, the only significant differences are the following:

The outside wing will see a greater airspeed than the inside wing, which will mean:

The outside wing will produce more lift than the inside wing, producing a rolling moment to the inside.
The outside wing will also produce more drag than the inside wing, producing a yawing moment to the outside.
On the other hand, the outside wing will also see a shallower angle of attack than the inside wing, which will partially negate both of the above effects. I'm guessing that the lift effect will be negated more strongly than the drag effect.

The nose will see relative wind from the inside of the turn (which will have no significant effect); and the tail will see relative wind from the outside of the turn, which will produce a yawing moment to the outside.
Since the rudder is deflected towards the inside of the turn, the vertical stabilizer will produce a rolling moment to the outside.

So my questions are:
Is my understanding of the rolling and yawing forces in turning flight correct? Are there any significant effects I've missed? And how large is each of these effects—which ones are the big ones, and which ones are insignificant? And most of all, how come there's an underbanking tendency in shallow turns, but an overbanking tendency in steep turns?

Tanner, in a steep bank there is a significant "sideways" component to wing lift that will result in relative wind yawing the nose into the turn, especially if the plane is also sinking (as at 45 degrees you now have 1/2 vertical fin 1/2 horizontal fin).  Elevator trim tightens the turn, increases sink rate, etc.  Spiral instability.

@Tanner Do you require further clarification on the subject? If not, would appreciate accepting the answer :)

@Jimmy I haven't yet had the time to fully read and think about your answer, but I probably will at some point in the next few days.

I think your reasoning is correct. However, I would say that the change in lift due to effective AOA on each wing from yaw rate is an order of magnitude smaller than that from airspeed. At high bank angle, the wing loading is higher, resulting in more inward turn and decreased spiral stability. While the yaw-out moment from the drag is also increased due to relative airspeed difference on each wing, the effect is smaller since drag is smaller than lift.
Let's look at it more mathematically. Static spiral stability is dictated by:
$$C_{l_\beta}C_{n_r}-C_{l_r}C_{n_\beta}>0$$
where $C_{l_\beta}$ is roll moment due to sideslip, must be negative for a Part 23 aircraft; $C_{n_\beta}$ is yaw moment due to sideslip, must be positive for Part 23; $C_{n_r}$ is yaw-out moment from yaw rate, where, as you reasoned, should be negative due to increased drag on the up wing and reduced drag on the down wing (due to airspeed difference from yaw rate); $C_{l_r}$ is the roll-in moment from yaw rate, where, as you reasoned, should be positive due to increased lift on the up wing and decreased lift on the down wing (due to airspeed difference).
At high bank angle, there is increased load factor (at 45deg, it's 1.4G). Therefore, there is increased lift and induced drag on each wing. The moment arm to induce the moment is about the same for each. However, if you look at the first order effect from the speed increase, it's:
$$\Delta F=\frac{1}{2}\rho (V+\Delta V)^2SC_x-\frac{1}{2}\rho V^2SC_x\approx\rho VSC_x\Delta V$$
So all things being equal, the larger the coefficient, the more pronounced the effect. And since lift is larger than drag, it wins out. (I'm still hand-waving here a bit since induced drag is squared of lift, so it's more nuanced).
With this in mind, you can see that at higher bank, $C_{l_r}$ increases more readily than $C_{n_r}$, therefore leading to reduced spiral stability.

there's a little too much left to the reader, I think. Your answer flows well, but when it comes time to look at the first order speed increase, none of the variables are defined, and their relationship to $C_l_r$ and $C_n_r$ is murky at best ("the larger the coefficient" <-- the larger which coefficient?). Could you clarify this section, please?

Underbanking tendency at a shallow bank angle will vary with design.  High wing dihedralled trainers need aileron to hold a shallow bank angle.  A symmetrical, aerobatic plane with little dihedral, not nearly as much.
Overbanking at high bank angle is a result of spiral instability, which is dependent on vertical empennage area (really balance of total fore and aft area relative to CG) and can be exacerbated by excessive static stability created by setting CG too far forward with a lot of nose up trim.  As plane rolls and slips, side force on the tail turns it into a spiral and speeds up the outside wing, creating a greater lift imbalance.  The elevator trim contributes to the spiral, tightening the turn.
Designers try to balance spiral instability with roll correcting tendency (sweep, dihedral, tall vertical fin, better fore and aft area balance).

That's the canonical definition of spiral instability. But it doesn't address the central question of the OP, why the difference between large and small bank angles?

A plane slips much less at a low bank angle.

For one, I fail to see why bank angle has anything to do with sideslip at coordinated turn. With all engines operating, sideslip would be small regardless of the load factor. Unless you are saying that lateral/directional stability derivatives change drastically for small betas, this would not explain the change in spiral stability.

A banked plane has a greater horizontal acceleration component, so all that area behind the CG (that was your directional stability friend) now makes your plane spirally unstable.  This is a common theme in aircraft design.

Where did you get this? Do you have a source?

A few years of building.  Basicly, in a shallow turn, the plane must create a slip, and yaw through the turn, rudder applied. As bank angle increases, the wing horizontal vector "pulls" the plane through the arc more.  At some point, depending on design, rudder is no longer needed, indeed, there is too much force on other side from the horizontal acceleration of the wing.  Useing small balsa gliders as models (in a crosswind) one can develop an understanding of leeward wing speed increase from tail area vs dihedral self righting.  Of course good piloting helps control too.


text:
What does "throttle is staggered" mean?
What does "throttle is staggered" mean? and how is it related to adjustment of MEC(Main Engine Control) in B737-300(CFM56-3C)?and which are safety issues regarding that?

You’ve asked 3 questions and given us very little to work with.  You’re rolling the dice that someone with a maintenance manual and very specific experience might jump in here, but you’d have a much better chance if you provided a full quote in context.  Then those with similar experience could at least stand some chance of deciphering a probable reason.

P.S.  “Staggered” just means the levers are not in the same position…

Michael, what is the risk of throttle stagger?

Where does your information about the term "throttle stagger" come from? I mean, did you hear it in a movie, read it in a flight manual, or what?

Saeed, per my first comment, tedder42's comment, and John K's answer, you need to explain where the term comes from!  If John's interpretation is correct and it comes from a pilot gripe then I don't see any real risk, it's more of an annoyance that they don't match.  But please clarify your question so we don't play these guessing games, and if you are in a position to fix the aircraft then by all means you need to get absolutely clear with the pilot and other maintenance personnel on both the meaning of the gripe and corrective action!!!  Don't fix airplanes off random internet advice.

If I was a mechanic looking at that snag, I would assume the  pilot is complaining the two thrust levers are way out of alignment when engine N1s are matched. They are usually never 100% perfectly aligned, but most pilots will start to complain if the stagger is more than, say, a quarter of the width of the lever handles.
This makes setting power a pain in the butt, and can be an issue in an abnormal procedure when you have to set go around thrust on a missed approach, and more care and tweaking is required by the pilot setting thrust. Basically, higher workload in abnormal situations is the risk factor.
The engine being non-FADEC, there is a need to check the rigging/adjustment between the thrust levers and the fuel control system, or within the fuel control system itself.

Does "snag" have the same meaning as "gripe" or "squawk"?  (pilot initiated maintenance action request)  I haven't heard that term before...

Yes.  Maybe a Canadian thing? I assumed it was common term in US as well.


text:
What are the main changes in CAP437 rev 9 from a Helideck Monitoring perspective?
CAP437 rev 9 was first published Edition 9 February 2023. In particular, what should a Heliops operator conducting operations on a "moving" helideck be made aware of. What training would an operator require assuming that the standard is applicable and enforced?

Are you asking for a hobby simulation, school, or for work?

this is from a professional standpoint.


text:
FAA and Eurocontrol waypoints with same ID
It seems that the FAA and Eurocontrol have waypoints with the same ID.
For example, the route between KJFK and LFPG for a recent flight reads as
KJFK..BETTE..ACK..VITOL.N73A.SUPRY.NATY.ATSUR..GAPLI.M25.ANNET.UM25.UVSUV.UM25.INGOR.UM25.LUKIP.LUKIP9W.LFPG/0555

How can one tell that the ANNET waypoint corresponds to the European area and not to the US? I mean in an automated manner, of course when looking at the map one can tell.

You seem to be asserting that there are two different waypoints with the same name, but the strip only shows one ANNET.  And what do you mean by "corresponds"?  Which continent's airspace the fix is within?  Because for that, (I know you said it...) look at the map.  There's no field in a flight plan strip for noting geographic jurisdiction of a waypoint.

Why are waypoints not named uniquely?


text:
P Factor vs Spiral Slipstream
Does anyone know of any real aeroplane or wind-tunnel tests that quantifies the effects of asymmetric propeller blade loading (P factor) versus the Spiralling Slipstream effect in creating yaw.
Which effect is greater?

I got the following results today in a Pitts S1S with a 180 HP Lycoming IO 360 and 76 inch diameter Sensenich 2 blade prop with 61 inch fixed pitch.
Upright in a 70 kt full power climb starting at about 3000 ft, wings level, ball in the centre. When the right rudder was released and the feet held clear of the pedals, the a/c yawed to the left about 45 degrees quickly. Then with the wings held level with right aileron and holding 70 kts, the left yaw continued in a flat turn at about 9 deg per second and this was allowed to continue for 180 degrees.
Continued below.

The Pitts was then returned to 3000 ft, rolled inverted and put into a 70 knot full power climb with wings level.
When both feet were held off the rudder pedals, the a/c yawed slightly to the pilot’s left, hardly discernible.

My initial deductions are that the vertical tail was mostly clear of the propeller slipstream when inverted due to the high angle of attack, and that the P-factor (which should have been the same inverted as upright) is a very small effect compared to the Spiral Slipstream effect created by  the propeller.
The ability to conduct a flat turn without rudder seems to show that the spiralling slipstream has a very large effect at high power and slow speed in aeroplanes like the Pitts S1

Any aerodynamics experts out there?

That depends on Angle of Attack (AOA), as well as other factors, including aircraft design. P-factor is caused by the angle between the free-stream airflow in front of the propellor and the propellor rotation axis. That changes as AOA changes.
Slipstream effect is caused by the impact of the corkscrew airflow created by the propellor impacting the vertical stabilizer.
So, for example, in my Long EZ, where the propellor is at the back, in the downwash from the main wing, P-factor is minimal at most AOAs. And the slipstream effect is nonexistent, since the corkscrew airflow from the prop is all behind the aircraft.


text:
What should I do if I lose situational awareness while in the pattern?
Let's say that I'm doing some pattern work in my favorite little Cessna or Diamond at my favorite little non-towered airport. Everything is going just fine, I'm on the downwind leg...
Or, wait a minute, am I on the crosswind leg? Which runway are we using today? I just heard another plane on the radio that I can't see; what did she say, again? Is she behind me or are we on a collision course?
In short, I suddenly realize that I don't have a full picture of what's going on here.
What are my options here, and how should I choose between them?
Here are my ideas, from best-sounding to worst-sounding:

Just climb out of the pattern, then fly a safe distance away from the airport, descend, and fly back into the pattern. I assume that after starting the climb, a quick radio call wouldn't hurt: "Wobegon traffic, Skyhawk eight three four sierra tango, climbing out of the pattern and going west." (I've always heard that you should never descend or climb directly into the pattern, but I've never heard that you shouldn't climb out of the pattern.)
Keep flying, keep looking out the window, and talk fast on the radio: "Aircraft at Wobegon, where are you again? I'm not sure exactly where I am, do you have me in sight?" (I'd feel stupid saying this, but it's better to speak up and feel stupid than to stay quiet and be stupid.)
Keep flying, keep looking out the window, stay quiet, and just try to figure out what's going on.

I don't mean to be rude, but have you actually flown an airplane?

@pericynthion I have, yes. Is there something stupid about my question? :D (I've got a whopping 5 hours or so in airplanes.)

Not stupid, I just wondered if perhaps you only had home flight sim experience - the idea of not knowing where you are in the traffic pattern is hard for me to wrap my head around, at least in an actual airplane with windows you can look out of. But I have a couple of thousand hours so it's become totally second nature to me and I guess I've forgotten what it's like to be a student.

@pericynthion Ah, that makes sense. Yeah, you're right; I admit that it seems like it would be hard, in particular, to forget where you are in the pattern at an airport with only one runway, since you can just look out the window and see where the runway is. Losing track of where the other aircraft are seems a lot more likely.

@pericynthion:  Though it's quite possible to lose track of other aircraft.  One of my least favorite memories is the time I was on a fairly long final in a sailplane, when some idiot in a Beechcraft flew under me to land.

Yep, very true, sometimes it's a zoo out there

As it happens, I've witnessed a pilot screw up departure heading by 180 degrees in a single runway airport, so yes, it is possible to lose situational awareness in a simple environment :)

Step 1, Don't panic  it's written right there on the cover.

It is the advice of the FAA that you should be looking out the window quite a bit when VFR in the pattern. According to this AC related to traffic patterns:

Collision Avoidance. The pilot in command’s (PIC) primary
  responsibility is to see and avoid other aircraft and to help them see
  and avoid his or her aircraft. Keep lights and strobes on. The use of
  any traffic pattern procedure does not alter the responsibility of
  each pilot to see and avoid other aircraft. Pilots are encouraged to
  participate in “Operation Lights On,” a voluntary pilot safety program
  described in the AIM, paragraph 4-3-23, that is designed to improve
  the “see-and-avoid” capabilities.

If you are worried you should (over) self announce, if you lose track of an aircraft you should do every thing in your power to make sure that the other aircraft know where you are in the pattern.

Self-Announce Position and/or Intentions. “Self-announce” is a
  procedure whereby pilots broadcast their aircraft call sign, position,
  altitude, and intended flight activity or ground operation on the
  designated CTAF. This procedure is used almost exclusively at airports
  that do not have an operative control tower or an FSS on the airport.

The FAA also offers lots of advice on how to fly a pattern here.

If you are confused somehow about your situation over an airport, and there are other aircraft around, head for empty sky away from the airport beyond the pattern/circuit and get reoriented. By empty sky, I mean if you think somebody might be nearby and you aren't sure where they are and don't have them in sight, identify a patch of sky where they're not, and head for that.  Don't climb or descend while doing this.  Most midairs are from aircraft on similar tracks that converge while one is descending or climbing, within a few miles from the airport.
The key is, you have various blind spots and you shouldn't head into the blind spots.  Head for sky you can see.
Yes announce your position and intentions, without cluttering up the channel with chatter.  Don't expect too much at your level. With practice and familiarity, your ability to think about multiple tasks will improve and your situational awareness will improve with it as you gain the ability to think outside the aircraft once your physical actions start to become automatic.

Aviate, navigate, communicate.
Tell yourself to keep calm.
Look around you: If your current heading is not taking you over the runway or towards visible traffic, keep your heading and altitude.
Look around you: is there any feature outside that you recognize? Chimney, church, lake, forrest? If yes, and the course there does not cross the runway or other traffic, make a standard rate turn towards the feature.
Announce your intentions, don't worry about specific phraseology, for example: "NXYZ is leaving ABCfield traffic pattern with heading 123 at 1234 feet" will do.
After you gain some distance from the field, and get yourself oriented again, approach the field according to local procedures. Keep aviating, navigating and communicating. Keep calm :)

Your DI will tell you your heading and you can work out which leg you are on from that.  If the runway in use is 09 and you're flying 270 then you're downwind.  If the pattern is left hand and you are flying 180 you're on base, if it is 360 you're crosswind.
Obviously, heading is not track.  It gets harder if your runway is 23 and there's a 20kt wind from 170 to allow for. But you could get a vague idea of where you are IF you've flown the circuit correctly before you lose situational awareness.
I think, in the pattern, you are more likely to lose awareness of where you are in relation to other traffic, stop paying attention to your height or (let,s face it, we've all done it ) fly the wrong way round the circuit, rather than forget what leg you're flying


text:
Is there research suggesting that VFR cruise altitude rules improve safety?
In the United States, 14 CFR 91.159 prescribes cruising altitudes for level flight under VFR:

(a) When operating below 18,000 feet MSL and

(1) On a magnetic course of zero degrees through 179 degrees, any odd thousand foot MSL altitude + 500 feet (such as 3,500, 5,500, or 7,500); or
(2) On a magnetic course of 180 degrees through 359 degrees, any even thousand foot MSL altitude + 500 feet (such as 4,500, 6,500, or 8,500).

In other words, planes going generally east use one set of altitudes, and planes going generally west use another set of altitudes.
Now, it's not obvious that these rules are the best possible rules for VFR cruising altitudes. Some alternatives would be:

No cruising altitude rules at all. All VFR flights select a cruising altitude arbitrarily.
VFR cruising altitudes are given as blocks instead of single altitudes. For example, planes going generally east cruise at 3,200 through 3,800, or 5,200 through 5,800, and so on.
Cruising altitudes are prescribed in such a way that aircraft with different courses are always given different cruise altitudes. For example, require aircraft to cruise at an altitude such that the 100-foot needle on the altimeter points in the same direction as the "N" on the heading indicator.

The Wikipedia article "Navigation paradox" mentions a couple of papers which state that random cruising altitudes would result in fewer mid-air collisions than the VFR cruising altitudes prescribed by regulations.
Is there any research suggesting that the current VFR cruise altitude rules do, in fact, improve safety? In other words, are there any studies which compare the current rules to at least one alternative, and show that the current rules are better?
(The specific rules I mentioned are the US FAA regulations, but I'm also interested in research about other countries' VFR cruise altitude rules.)

I think most mid-air collisions (at least with GA aircraft) occur at low altitudes, on clear days, and around points of interest (airports, VOR's, or other landmarks) that are below the 91.159 rule altitude. These happen at "random" altitudes...

For research purposes, the UK (and other European nations?) used to use the quadrantal rule, where heading 00-89 was odd-thousand feet (5000), hdg 90-179 was odd+500 (5500), 180-269 even-thousand (6000), and 270-359 was even+500 (6500). They switched to the hemispheric rule used by the rest of the world (?) a couple of years ago.  Maybe a study suggested it was safer? Or maybe a study suggested that "the same thing everywhere" is safer, as opposed to the specific rules. {shrug}

I always presumed that vfr altitudes were simply to keep them from interfering with ifr traffic. If there's a vfr aircraft that atc can't see they would prefer it not be at the same altitude unless climbing/descending

@TomMcW That probably justifies the +500 but not the even/odd rule.

Whenever the FAA proposes a rule they lay out their justification in a notice published in the Federal Register. The problem with 91.159 is that it was created with pretty much he same wording as today (at least for airspace below 18000 ft) within the first version of Part 91 published in 1963. This "FAR" version was a mass move/renumber from the old Civil Aviation Regulations (CAR) version without additional comment. So you need to find the old CAR reference and the associated Federal Register publication. Those records aren't easily searched.

You could probably research this yourself with the NTSB accident database. But you'd have to figure out how to classify accidents into mid-air and otherwise, then review those to find which ones might be caused by altitude conflict, then tally by year. Lots of work, but a good one to assign to undergrad students. :)

Searching Scopus for (VFR OR 'Visual Flight Rules') AND safety in title/abstract/keywords yields two publications (out of 99 hits) that might contain information (or references to other sources) on the safety performance of the current VFR system with alternatives.
Prinzel et al. (2011) - Flight deck interval management and delegated separation for equivalent visual operations

An emerging Next Generation Air Transportation System concept Equivalent Visual Operations (EVO) can be achieved using an electronic means to provide sufficient visibility of the external world and other required flight references on flight deck displays that enable the safety, operational tempos, and visual flight rules (VFR)-like procedures for all weather conditions. Synthetic and enhanced flight vision system technologies are critical enabling technologies to EVO. Current research evaluated concepts for flight deck-based interval management (FIM) operations, integrated with Synthetic Vision and Enhanced Vision flight-deck displays and technologies. One concept involves delegated flight deck-based separation, in which the flight crews were paired with another aircraft and responsible for spacing and maintaining separation from the paired aircraft, termed, "equivalent visual separation." The operation required the flight crews to acquire and maintain an "equivalent visual contact" as well as to conduct manual landings in low-visibility conditions. The paper describes results that evaluated the concept of EVO delegated separation, including an off-nominal scenario in which the lead aircraft was not able to conform to the assigned spacing resulting in a loss of separation.

Quinby (1980) - General aviation operating requirements for the 1980's

This paper presents a review of the use of the airspace and the air traffic control system. Safety, capacity and efficiency of this use under Visual Flight Rules (VFR) are compared with the evolving constraints imposed by operations under Instrument Flight Rules (IFR). The concept of Electronic Flight Rules (EFR) as developed by Topic Group III on Freedom of Airspace in the FAA’s 1978–79 E & D Initiatives Process is reviewed. The potential for conservation of air traffic control manpower and aircraft fuel is further developed. Promising areas for further technical exploration are noted. The paper concludes with some considerations for co-existence of VFR, IFR, and EFR traffic during a transition period.


text:
Is this paragraph about the dihedral effect in the FAA's Glider Flying Handbook correct?
I've been reading the FAA's Glider Flying Handbook, 2013 (FAA-H-8083-13A). In chapter 3 ("Aerodynamics of Flight"), the book is discussing stability. On page 3-12, it states:

Dihedral is the upward angle of the wings from a horizontal (front/rear view) axis of the plane. As a glider flies along and encounters turbulence, the dihedral provides positive lateral stability by providing more lift for the lower wing and reducing the lift on the raised wing. As one wing lowers, it becomes closer to perpendicular to the surface and level. Because it is closer to level and perpendicular to the weight force, the lift produced directly opposes the force of weight. This must be instantly compared to the higher and now more canted wing referenced to the force of weight. The higher wing's lift relative to the force of weight is now less because of the vector angle. This imbalance of lift causes the lower wing to rise as the higher descends until lift equalizes, resulting in level flight.

That doesn't sound right to me.
This paragraph says that there's more lift on the lowered wing and less lift on the raised wing. That's not true, is it? The amount of lift only depends on a wing's airspeed and angle of attack, not on the wing's bank angle.
The paragraph then explains that the lowered wing produces more upward lift than the raised wing. I think this is true, but it's not relevant, because upward lift isn't the only lift which contributes to rolling moment. Rolling moment depends on the total lift (and the direction of the lift).
All in all, I think that dihedral can't produce a stabilizing rolling moment in the way that the book says that it does. Any stabilizing effect must come from a difference in airspeed or angle of attack between the two wings.
Is the book's description of dihedral correct?

Possible duplicate of How does the dihedral angle work?

I agree with you. Dihedral effect requires sideslip. They seem to be describing what people call the "pendulum effect," which is due to the dihedral but is not the same thing.

@Pilothead I'm asking about this one particular explanation of the dihedral effect. Only one of the answers on that question addresses the FAA's explanation. That answer essentially says that the FAA's explanation is correct, but it's also downvoted, and there are comments which say that the answer (and therefore the FAA's explanation) is not correct. So, there is apparently no answer to that question which correctly answers my question.

@TomMcW: No, please not. There is no pendulum effect in airplanes.

@PeterKämpf I was wondering if you'd see that. I feel in some aircraft there can be if the center of lift is WAAAY over the cog, like in a powered parachute.

@PeterKämpf I was going to say the "fabled" pendulum effect, but somebody mentioned a powered parachute once and I couldn't reconcile it

@TomMcW But even a parachute's lift vector goes straight through the mass below it if there is no sideslip, regardless of bank angle.

@PeterKämpf Are you saying that a hang glider that controls roll by weight shifting actually uses some other means to control roll? It does the same with pitch.

@PeterKämpf I think I'll post up a question about it later so I can figure it out. We haven't had a question specific to the "pendulum" thing.

I don't think this is a duplicate. Although the question is about the same topic, this question asks about understanding a particular detail which isn't really mentioned in the other question or its answers.

We have 2 cases here to consider, turning and straight flight.  The statement "lift vector goes straight through the mass below regardless of bank angle" may refer to "ball centered" coordinated turn.  Our newer modelling is showing, in straight flight, the VERTICAL lift vector and CG displacement (from side force gust roll) will create a roll torque to return to level.  This effect is the archaicly termed "pendulum".  Could our esteemed senior member confirm these 2 cases exist?

@JuanJimenez Please post that as an answer, not as a comment. Thank you.

No, the explanation is not correct.
Tanner, you are right when you say that lift does not depend on bank angle. Lift is caused by a pressure difference, and pressure can only act perpendicularly to a surface. Therefore, the lift on each wing and its lever arm to the center of gravity won't change with bank and no "correcting" rolling moment is created.
Instead, what does happen is a side force from the wing's bank angle which will accelerate the airplane sideways. This in turn will result in a sideslip condition, and only now will a dihedral effect show up: By changing the angle of attack on each side differently, the sideslip in combination with dihedral will create a correcting rolling moment.
As you correctly observe, a stabilising effect can only come from a difference in angle of attack between both wings, and that only occurs in a sideslip.

The analysis by the asker of the question is correct, and the paragraph in the FAA's "Glider Flying Handbook" is not correct.  The same is true of any "explanation" of dihedral that doesn't rely on the difference in angle-of-attack between the two wings generated by sideslip.
Furthermore, it's important to note that sideslip cannot be explained simply by noting that when an aircraft is banked, the tilted lift vector contains a sideways component, or that "from the point of view of the aircraft, lift is still acting in the plane of symmetry, but gravity does not and will cause it to sideslip", as is sometimes stated.  (For example, we find something close to this in Martin Simons' well-known book "Model Aircraft Aerodynamics", as well as in many other sources.)  Those are essentially Aristotelian concepts rather than Newtonian concepts. A continuous net sideways force component causes a turn, not a sideslip.  Force causes acceleration, not steady sideways motion, and turning is a curvature in the flight path which is a form of acceleration.
For ideas on the actual cause of sideslip during banked, turning flight, see this related answer How does the dihedral angle work?
The "explanation" of dihedral is only one of several conspicuous errors in the FAA's "Glider Flying Handbook".  For example, it doesn't even contain an accurate depiction of the L-D-W vector triangle to explain why the L/D ratio is the same as the glide ratio through still air-- such a diagram is fundamental to understanding gliding flight.  It also claims that it is dangerous to slip gliders with swept leading edges due to the resulting slip-roll coupling-- totally overlooking the much larger slip-roll coupling created by dihedral (e.g. any modern glass ship other than Fox, Swift, etc) and/or high wing placement (e.g. 2-33, 2-22) in a typical sailplane.

Yes, it is correct.  Consider an airplane with a positive 5° dihedral to its wings.  If the lift the airfoils generate is perpendicular to its span line, this means that in level flight the lifting force parallel to the plane’s vertical axis is L*cos(5°) for both wings.  If the airplane is rolled 30° to the left, then the lift generated by the left wing parallel to the force of gravity is L * cos(25°) whereas the lift generated by the right wing is L*cos(35°).  This imbalance in lift causes a moment about the plane’s CG, causing it to roll back level and providing both a positive lateral static and dynamic stability.

It looks to me like you're only looking at the component of lift which is parallel to the force of gravity, and not the component which is perpendicular to the force of gravity. Is that right? When you add in the component which is perpendicular to gravity, is there still an overall rolling moment, or is the rolling moment canceled out to zero?


text:
At a non-towered airport in the US, what should I do if I hear a medevac flight waiting to take off while I'm turning base?
I'm in the left downwind at my favorite non-towered airport. Just while I'm making the turn to base, I hear a radio call on CTAF: "Such-and-such Traffic, Medevac 123, holding short runway 31." They don't make any requests or say anything else; they merely announce that they're there, waiting for me to land and get clear.
Since they're a medevac flight, should I abort my approach and let them take off immediately, or is it fine if I simply land and vacate the runway as soon as practical?
If I abort the approach, what's the best way to do that, given that I'm on the base leg now? Continue past the runway and make an upwind leg? Just turn right and exit the pattern completely, and then come back once the medevac flight is out of the way?
And whatever the right thing to do is, what radio call should I make? I assume that there's something more standard than "Medevac 123, Diamond 456, I'm just gonna continue past the runway and make an upwind leg so that you can take off right away."
(This happened in a 2-seater I was riding in today. In this case, the pilot decided to simply land and get clear of the runway quickly.)

The best thing you can do is not be one of their customers.

The most obvious thing to me would be to just talk to them:

Medevac 123, this is the Diamond on base for 31, do you need to expedite your departure?

If they say no, then just continue and land as normal. If they say yes, then I'd get out of their way:

Medevac 123, roger, we'll extend our base and fly a wide upwind to let you  out

I wouldn't worry about standard phraseology too much, the critical point is to make sure you both understand each other and if there's no well-established phrase for what you need then just say whatever seems clearest.
Extending base to upwind has the advantage that it keeps you in the pattern so you can see what's going on as the medevac flight departs and you don't waste too much time going around the pattern again. (Although unless I have an emergency of my own I'm more than happy to make whatever detour is necessary to help out a medevac flight.)
Turning out right puts the pattern behind you and if you turn too early then you're potentially turning into other traffic on a long final, so it wouldn't be my first choice. But I don't think there's any standard way to break off from base and there are lots of possible variables (terrain, traffic, airspace etc.) so it's up to the pilot to decide what's safest at that particular moment.

This is good advice. I used to fly fixed wing under the Medevac callsign; in my experience most flights were nowhere near so time critical that we would need another aircraft to go around to give way to us. Such is generally the nature of fixed wing Medevac; rotary wing Medevac might well be different, but is unlikely to lead to this scenario either.

From a phraseology point of view, I would alter the second call: too  many details. Something like: "making orbits to let you out" or "extending circuit to let you out" I think would fit better.

I ran into this situation a couple of times. 1st time, as passenger, my pilot took this approach, medevac said "No need, continue as normal". 2 other times I took same approach myself . Again a "no need" response on the 2nd time and on the 3rd I got "Not strictly needed, but would appreciate if you could". Made another circle and got a thank you from the medevac after they had taken off. I later ran into the medevac pilot and he said they had small girl with a broken leg. No medical hurry, but she and her mother (also onboard) were quite nervous (1st flight). The sooner it was over the better.

What path exactly would be an "extended base to upwind"?

@Czechnology Assuming it's a left-hand pattern I meant to continue on base past/through final and then turn left onto the upwind leg. I think most people would understand it like that, at least in the US, but maybe there's a better way to put it.

Personally I don't care for "making orbits" or "extending circuit".  I would say "Medevac 123 go ahead, Diamond is taking it around."  I would then fly a normal pattern, and offset on the upwind leg just enough to keep him in site during his take-off roll.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Faults on Gulfstream G550/C-37B repairable in < ~3hrs without aircraft specific tools or spares?
Endeavouring to meet your requirements for specificity. brevity, question as title, etc.
I am an author seeking a realistic fault/issue for a Gulfstream G550/C-37B meeting the following criteria:
1/ Fault/issue renders the a/c not airworthy, i.e. take-off disallowed without repair
2/ Fault/issue can be rectified by one or more qualified mechanics within ~3hrs
3a/ Fault/issue plausibly attributable to heavy landing (on well-maintained surface)
OR
3b/ Fault/issue plausibly attributable to other issue arising in the course of hot-refuelling
From a narrative point of view, the more obvious the defect (and its significance) to a non-aviation specialist/more spectacular the symptoms the better.
In case the location is relevant, it is written to occur on a US Air Base (outside the USA), a/c landing just after sunset, at max range. Aircraft must fly on through the night after the repair.
(I find technical inaccuracy where technical accuracy is practicable to be detrimental to the reading/viewing experience, so I would like to be accurate if I can. No offense will be taken if this question is deemed OT, or otherwise unanswerable, in which case I will just make something up on the basis that it was not practicable to be accurate... but I thank you in advance for your generous interpretation of the request for assistance)
I considered landing gear failures of various kinds, but would expect them to lead to other structural damage not repairable within the allowed time.

A heavy landing after a max range flight isn't very plausible, because fuel is a major contributor to weight.  You'd probably be at your lightest with possibly only reserve fuel remaining after a long flight.  But a heavy landing, you could spectacularly blow both main tires, or smoke the brakes trying to stop...

@MichaelHall Thanks for the comment on "heavy landing" -- I meant that the pilot put the a/c down hard in order to stop in the shortest distance possible: pilot puts down short on 2.7km paved area to stop in 900m and have 1.8km to take off again because a/c is hot-pitting. If there is better terminology for this please let me know (as a passenger, I tend to refer to landings in which the a/c just seems to drop onto the runway as "heavy" as ordinary language use such as "he fell heavily", where weight is not a consideration)

Understood.  BTW, what you are referring to is a “stop and go” which is done for training, but an aircraft would almost never stop on the runway.  Even in the biggest hurry where the hazards of hot refueling are acceptable the aircraft would likely taxi clear of the runway to refuel.

@MichaelHall Thanks for the terminology. Yes, I'm sure an a/c would "likely taxi clear of the runway" in real life, that would be sensible, but this is an action thriller and they've only got hours to save the world :) (i.e. every corner gets cut for a) speed b) rule-breaking c) because it's an emergency, dammit and d) on general principle for urgency -> excitement). BTW I think I'm referring to it as a very "hard landing" now, but ~2.1g on the CMC so no mandatory inspection for that ;)

Ok, just speaking as an old Navy pilot who has smoked brakes, blown tires, and hot refueled before, I think a more plausible scenario would be blowing tires or overheating the brakes trying to expedite getting clear of the runway to meet the fuel truck already waiting at a certain taxiway rather that trying to stop with enough runway to take off again so that the truck could refuel me on the runway.

... or skidding onto the grass being too aggressive making a turnoff and needing a tow vehicle to get back on the pavement.  Just a personal opinion though, and it is fiction after all!  Let us know when it's published, I'll buy a copy...

@MichaelHall I've made a note to return with publication news :)  If I knew how to reach individuals I would invite you to be a beta reader, if you're into slow-burn thriller/action stories. Thx for the input.

One plausible scenario would be runway contamination leading to tire damage and swap or otherwise necessary inspections after someone on the ground notices the impact marks.
It is not unheard of that departing aircraft drop something on runways, and other planes then run over the debris.  Also wildlife sometimes wanders on runways and gets struck by planes.
Birdstrikes are somewhat common at lower altitudes, but they are usually quite noticeable when they happen. Anyway, I've personally had to wait for two hours for an ok from engine manufacturer after a bird struck the engine cowling. The bird didn't go through the engine, but the dent had to be photographed and the engine manufacturer used the photo to asses the severity of the damage (a fist sized dent, about 1/2 inch deep). Flight was ok'd.
Those more versed with the plane type may have some more technical suggestion on borderline technical/MEL issues that require approval from dispatch or some other entity.
As mr Hall pointed out in the comments, a hard landing is not a very plausible scenario after a long flight.

+1 on birdstrike(s). Flying thru a flock of small birds could leave blood & feathers in all sorts of visible (describable) places, including the windshield(s).  A bad enough bird splatter could obscure the pilot's (or pilots') vision. Those are easy enough to fix with rags & windex; add dents on engine cowl to be measured & photos sent off, you could easily have a fun-filled 3 hours of waiting for the jet to be pronounced airworthy again.

@jpe61 Nice visual for description, thanks - a very useful scenario; I think I'll use it. Will accept afterwards. I have a complication of hot-pitting but I can turn one engine off for inspection (I went with brake issue while waiting for a more informed answer, just to have something to write around - brake issue being traced to a loose hydraulic hose.

@RalphJ Thanks for the extra visuals! How long would "inspection" itself take and who would perform it? (on a US Air Base)?

Inspection for the splatters, not long itself (basically, time to windex things clean at each spot + visual inspection of the surfaces). Getting a mechanic to the aircraft could take longer... quicker if the one-star running the base is involved, slower if the request gets passed thru multiple levels of organization. Photos of dents are quick; sending them off for evaluation... you hear back whenever. An hour or 2, easily. Depending on how big the MX unit is + what they care for, a tech qualified on C-37s might be plentiful, or quite rare: "Didn't Sam used to work on those? Where's he at now?"

@RalphJ Again, thanks. (But "MX"?) NB the fictional mission has so much pull the 1* doesn't get to do anything except say "Yes Sir/Ma'am" so no holdups there. I'm not going to dwell on details, just wanted to make sure I didn't say anything obviously stupid in a plausible scenario. Thx.

"MX" = Maintenance.


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USAF Formal language for Control hand-off
Within the United States Air Force, when pilot/copilot exchange control of an aircraft is there formal, required language, such as "You have control..."/"I have control..." and if so, what are the specified forms?
And if departure from these norms is either permitted or de facto, what else might be said, e.g. "Your plane"/"My plane", etc.
Input from other contexts (Navy, commercial, etc.) are also welcome for general information (and general site value) as long as the context is clear, but I am specifically asking about the USAF initially.

In early Navy training in tandem seat aircraft, (where you couldn't see the other pilot's hands) we actually used a 3 step transfer process.  (Give, take, acknowledge.)  For example, "You have the controls" - "I have the controls" - "Roger, you have the controls".
I seem to recall this relaxed a bit later in the program.  And outside of training, in dual controlled transport category aircraft with crews who flew together regularly and sitting side by side, that might relax even more to match your example in the second paragraph, i.e. "my plane" - "roger, your plane".

Thx Michael. Give, take, acknowledge - final acknowledgment step makes good sense.

@JulianMoore, yeah except now that I think about it more it may be been because they were tandem seat aircraft, (front and back) so you couldn't see if the other person had their hand on the controls.  I think it might be excessive for most circumstances otherwise.  I edited my answer somewhat to mention this.

Thx again; good clarification. Will wait a little longer just in case there's a specific AF answer, otherwise I'll assume all aviators are the same (that should put the cat among the pigeons :) )


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How long does it take the Predator UAV to reach cruise altitude?
For applications such as UAVs, especially military ones like the Predators and Reapers, do the same regulations as light aircraft apply due to their structure?
Or, does the absence of a human operator enable a higher rate of climb and descent? How long would the UAV traditionally take to climb to its cruising altitude then?

It's an interesting question title, but there are three separate questions being asked. Could you bring some more focus to this question and concentrate on just one part? You can always ask the other parts as separate questions.

Naïvely, I wouldn't expect that the climb rate could be greater than the engine power divided by the weight of the drone, which for a fully loaded Predator (using the specs from Wikipedia) works out to about 1700 feet per minute.  There may be some subtleties of aeronautical engineering that I'm not taking into account, though.

Aircraft are aircraft, humans in the aircraft are just another issue that affects performance.  UAV's don't generally have fixed cruise altitudes, it all depends on the mission parameters.


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What would the effect be of flap deployment on a UAV such as the Reaper or Predator?
I've read answers that said that the climb performance is usually worse with flaps extended, and the pilots would, if they could, just retract them and get into a clean config as soon as possible. However, i believe that applies mostly to transports, which have a higher gradient.
For designs like the Predator or Reaper UAV, which take-off and land essentially...flat, wouldn't flaps be more beneficial to help their climb? Albeit, having to reduce their deflection at intervals to reduce drag?
And if so, what do you think would be the altitude at which retraction would occur? I've tried to find information, but so far have only landed with a Boeing document that claims the typical flap retraction height is 3000ft.

Does this answer your question? Why do flaps retract?

the climb performance is usually worse with flaps extended

That depends which parameter needs to be maximized. If you want to climb as steeply as possible, flaps will definitely help. If, however, you want to cover some distance while climbing (en-route climb), you better retract them.
Flaps will shift the optimum operating point of a wing to a higher lift coefficient. Their deployment will also lower the zero-lift angle of attack so the fuselage attitude will be more negative at the same speed. This is helpful for designs like the MQ-1 and MQ-9 since their tail strike angle is only 5.3 degrees. Taking off and landing with flaps down will help to lower take-off and approach speeds and shorten their runway requirements.
The wing airfoil of both airplanes is already highly cambered which together with the high aspect ratio indicates a one-point design for longest loiter time, flying mostly at the same dynamic pressure and attitude.
Regarding drag: Flaps help to reduce drag when used properly. A simple camber flap will not change the coefficient of drag within a deflection range of ±15° (more for short flap chord fractions, less for deeper flaps) but will shift the optimum angle of attack for best L/D to higher lift coefficients with more positive flap angles. Basically, flaps allow to pick speed independent of altitude (within limits, of course). Flaps up if you need to fly faster, flaps down if you need to slow down.


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Do promotional flight routes have a historical precedent?
Right now, a Dreamliner is flying a rather strange path over the USA (see below). The plane took off from Boeing Field airport near Seattle, and is 'drawing' a virtual copy of itself on the map of the USA before flying back home.
As flight trackers are a relatively recent phenomenon, I was wondering: is this the first time something like this ever happens, or is this a tradition in aviation which I'm not aware of?

Permalink for the flight.

Wow, a turing complete Aircraft. Cool!

Related: How are special flight paths coordinated with ATC?

It's not the first time they do it. Back in 2012 they wrote 787 and the Boeing logo:

Planes have been drawn before by others as well.

I don't have a picture,  but Boeing has also flown a "12" over Washington state.  This was a reference to the fans of the local football team, the Seattle Seahawks.

Looks like they (Boeing) have gone from 8-bit graphics to 32-bit in the meantime, too!

One of the first examples I recall of this sort of thing was when a Gulfstream aircraft wrote "GV" over the US in 2007:

One could say that this has been a "tradition" for at least 10 years now.

It turns out Boeing has done this earlier this year as well; on February 11th, a 737 MAX painted the letters M A X over the North-Western states:

(source: Boeing's Twitter account)

Probably best to note that it's not really "promotional" -- Boeing had to do an 18 hour endurance test of the Trent 1000 TEN engines so they were going to be up there flying around anyways. So why not have some fun with it?
When those pictures came out it wasn't in a Boeing press release, it was some people who noticed by watching FlightRadar24 and other sites :)


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Is it true Wynantskill, NY has a real problem with aircraft noise from Air Force, or other aircrafts? Thank you
Is it true Wynantskill, NY has a real problem with aircraft noise from Air Force, or other aircraft? Looking to buy a home, but do not want this problem I may have heard on NPR. Thank you.

Define "problem"...  For some it's the sound of freedom!

Local zoning authorities may have actual measured data on that, if the area is considered to be a high risk area for aircraft (or any other) noise.

Performing a quick Google search resulted in numerous complaints about dogs barking and atv use (both during the daytime, no less!) but nothing about aircraft. And IIRC the one I saw about ATV's was named Karen... for real.

The nearest military air operations to Wynantskill would be the Air National Guard operation out of Schenectady County Airport - KSCH. Neither runway lends to an approach or departure in the direction of Wynantskill and all the instrument approaches are more or less West of the ALB VOR. There are no MOAs or Restricted airspace that overly that area directly. Thus there is no reason to believe military overflight is any more of a nuisance there than it would be anywhere else. This NYS site offers some reassuring info on that front (bolded for emphasis):

While high-performance military aircraft train over northern New York,
the New York Air National Guard does not operate aircraft that may
generate high noise levels or sonic booms.


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Can you log PIC time with an instructor without being currently enrolled in a flight school?
Been doing discovery flights with a friend who is a CFI. Am I legally allowed to log PIC time without being enrolled at a flight school? Want to know before logging /flying.

PS enrolling in a flight school in May just getting some experience.


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What is the name of the pedal assembly in an aircraft cockpit?
I'm proofreading a document about rudder control systems and client insists on calling the pedal assembly under the pilot's feet the "rudder". Would this ever be used?

757toga’s answer explains it well, but an example sentence might yield better feedback about whether the term is being used in the correct context.

Proper term for the collection of parts that includes the pedals, the struts they are mounted on, and any bearings etc, up to the push rod(s) that drive the rudder control circuit, is "Rudder Pedal Assembly".
If you were describing it in a technical document that describes the control system, that's the term you would use.
If you were describing it just for the pilot's benefit, so he/she knows where to put their feet, you would just say "Rudder Pedals".
Never "Rudder", that being the swingy bit at the back.

It would very common for an instructor to say "give it some more right rudder", but "step on the right rudder" would be unusual, and "put your feet on the rudder/s" would never be used.  The phrase used in the latter two examples would almost always be "rudder pedals/s".  Certainly a mechanic or designer would never refer to the pedal assembly as the "rudder".  The answer to your question is "no".


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Could the US military have harnessed the Chinese observation balloon and accessed it without destroying it?
I guess that if it was possible for the US military to have gained control of the Chinese balloon without destroying it, then they would have, especially since they are trying to gather fragments of it from the ocean. And I have no expertise in either aviation or military technology. But still, I second-guess the decision to destroy the balloon before trying to take control of the pilotless balloon. However, I hope to hear some experts chime in on this.

3 options:

Physical capture.
Take control.
Shoot the balloon and pick up the pieces.

1 -  Nothing to capture it with.
Early on, the USAF sent up a U-2 to take a look. Get some eyeballs on the thing. For the shootdown, the F-22. Those are about the only 2 (known) aircraft to get up to that height.
Neither of which have any functionality to 'grab it'.
2 - Taking control otherwise might have been usurping the control mechanism? Because apparently it could steer. Given the short timeline while it was still over US airspace, reverse engineering an unknown control signal would be pretty difficult, if not impossible in that timeline. Especially if the control signal was sent and received UP to a satellite.
But it may not have been remotely controlled at all. Many current UAVs can fly a preprogrammed route. From the Global Hawk, to a Reaper, down to a $500 DJI. Once it takes off, its all hands off. It just needs to talk to the navsat constellations for location verification. And its not like the places it flew over were unknown. Grand Forks AFB(RQ-4), and Whiteman AFB (B-2) don't actually move.  So plug those coords in, and let it fly itself.
3 - Shoot the balloon and pick up the pieces. Which is what they did.

If using guns was practical, would it be possible to just make so many holes in it that the balloon turned into a parachute instead? I'm thinking of something comparable in effect to shooting it with a very large shotgun.

Apparently the Canadians tried the gun thing with an F-18 and smaller wayward weather balloon. It didn't work. While there were holes, it was still drifting. I expect there was a lot of shared info about that attempt.

https://aviation.stackexchange.com/questions/97384/if-a-balloon-lies-within-gun-range-why-would-a-21st-century-warplane-shoot-it-w


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Sources for Python Codes to do some aerodynamic Calculations
I am currently working to design a wing. I basically want the Python code which would take the coordinates of the airfoil (.dat file), freestream velocity, Span (b), planform of the wing as input, and give all the characteristics of the wing-like Variation of lift and lift coefficient, drag, etc along the span and variation with angle of attack.
I don't think this is the kind of question I can ask here. But, if it isn't, then pls tell me where to post this query. If you feel like you can help, pls do.
I have googled but the sources were too messy and didn't have a good presentation of the code.

Everything you need is very well described in the classic Low-Speed Aerodynamics by Katz & Plotkin. Have fun with it

Searching python aerodynamics library provide several solutions, that you can evaluate, looking at the documentation: AeroPy, AeroSandbox, libxfoil, ... and you can look at PyPI and conda-forge repositories.

As @sophit alludes, you could certainly write a code to do this kind of calculation yourself.  You would learn the most about the theory and implementation.  I recommend you do this at some point.
There are also lots of Python or Matlab codes like this laying around.  You're looking for a lifting line theory (LLT) or vortex lattice code (VLM).  Some of the raw codes are suspect, others are meant for an experienced user to hack on, and yet others are meant to be used as a turnkey tool.  Good luck figuring out which you've found.
There are also some other tools that are clearly meant to be used without having to write code.  These include AVL, XFLR5, Tornado, and VSPAERO.  They each have their pros and cons -- mostly in how easy it is to set up and get to a first solution.
Your teacher or advisor likely has a preferred tool -- one that they are familiar with and will be able to give you advice.  You might want to start there, that way you know you can get help nearby.


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Moving from 2D wing to 3D wing design
In terms of the design perspective of an Aircraft, once we decide on the airfoil that would be used for the wing, how would an Aerodynamics Engineer (or you) proceed to construct the wing? The platform of my wing would be a rectangular + tapered wing. So, I am only looking to find the optimal Taper ratio and dihedral angle.
The main idea would be to get as close to the elliptical lift distribution as possible. But, how would we approach it? It is not as if we would try all kinds of combinations of taper ratio and dihedral and compare all of them and see which is closest to elliptic dist. It would be time-consuming and tedious as there would be a large number of combinations (possibilities).

Why wouldn't you try all kinds of combinations?  This is one of the fundamental ways design is performed.
Design is inherently an inverse process -- we start with desired performance and work to find the system that achieves it.  In rare situations, we can analytically solve inverse problems directly, but most of the time, we end up having to use some sort of guess and check or repeated evaluation.
In some cases, people have run many solutions before us -- we can use their results, charts, curves, or experience.  But you have to find that set of data or knowledge and make sure it applies to your situation.  In this case, you're really relying on someone else running lots of combinations.
If I were to assume you're at the start of your Senior Design project -- let me assure you, running a lot of cases and doing a lot of iterative guess and check is going to become a very familiar activity.
You say you already want a planform with poly-taper -- rectangular inboard and simple taper outboard (Like a Cessna 172).  The dihedral will not substantially effect the load distribution (how close to elliptical).  So why not set up a tool and compare wings with taper of 1.0, 0.8, 0.6, 0.4, 0.2, 0.0.
If you use zero twist and an un-cambered airfoil, you can isolate the effects of the planform.  Run all the cases at the same angle of attack.  Record the lift and drag coefficients.  Both will be different, so you will want to process them into equivalent induced drag factors -- either Oswald e or the K in CD0+KCL^2.  You know that the zero angle of attack case should result in zero CL and zero CDi.
You can also plot the six lift distributions on top of one another.  You might also want to plot the lift coefficient distributions and compare them.
For this, you'll want to use AVL, Tornado, XFLR5, VSPAERO, or another similar tool.

Sometimes the process may seem direct, but other elements come into play.  As an initial part of the process, the designer may have an idea regarding the plane, its weight, and required power.  If the design proceeds, scheduling may begin where estimates are made of the materials required to assemble the plane.  During this process, the weight of the aircraft is more closely estimated.  Afterwards, comes refinements such as finishing the design of the wing and wing spar.  But even after a plane is built, the design process may not be complete.  Charles O'Neill presents an analysis of the wing of three successive versions of the Piper Cherokee, each new wing a modification and improvement of its predecessor. Here is a link to Dr. O'Neill's analysis.  Information in his analysis includes the wing section, a perspective on why that airfoil was chosen, how the airfoil compliments construction of the wing, and how aerodynamics of the wing were improved by successive modifications on an already successful design.  Dr. O'Neill also comments on the methods used and resulting limitations in his analysis.  In my estimation, a worthwhile read given the perspective of the question being asked.

An aerodynamic engineer would maybe strive for an elliptical circulation. But not an airplane engineer.
In 1933 Ludwig Prandtl published "Über Tragflügel kleinsten induzierten Widerstandes" in the Zeitschrift für Flugtechnik und Motorluftschiffahrt. 17 years later R.T. Jones came to the same conclusions in NACA-TN-2249. The 2013 article "Lift Distributions for Minimum Induced Drag with Generalized Bending Moment Constraints" by David J. Pate and Brian J. German goes one step further and optimises drag at a lower and structural mass at a higher lift coefficient.
The optimum wing for lowest drag has less than elliptical lift towards the tips and more taper, but more span than a wing with elliptical circulation. This reduces the root bending moment and, consequently, wing weight. If less lift has to be produced to carry the wing, drag is also lower. Scaling laws mean that structure becomes more important as aircraft grow in size and mass. You know that elephants have much more massive legs relative to their body size than antelopes (or even ants, for an even more drastic comparison), since body mass scales with the cube of linear dimension while structural strength scales only with the square of linear dimension. This means that wing spar weight will be proportionally higher for larger aircraft.
As a consequence, insects have more elliptic wings than albatrosses, and model aircraft have optimum wings which are much more elliptic than the optimum wing of an airliner. The optimum shifts from an elliptic load distribution at very small scales to an almost triangular distribution at large scales.
Once you know the size of your airplane, you vary taper and span such that a given excess lift (needed to carry the fuselage, tail, systems, crew and payload) can be produced with the lowest drag. This requires to consider aerodynamics and structure together. Chord is the result of the required wing volume.

how would we approach it? It is not as if we would try all kinds of combinations of taper ratio and dihedral and compare all of them.

You're right.
Unless you are designing a radically new aircraft then there's no need to reinvent the wheel.
What you would do is just using a similar airplane as a basis and build upon it your new project. You want to design a new long-range, wide-body twin-engine jet airliner? You use the A330 as a basis and develop what you will call A350. You want to design the best-selling among four-seat, single-engine aircraft? You use the Cessna 170 as a basis and develop what you will call Cessna 172. And so on.
The basic aerodynamics characteristics of most of the wing layouts out there are well known so there's really no need to run thousands of simulations to discover that, for example, the wing for a jetliner should have a taper ratio around 0.4, aspect ratio around 9.5, laminar airfoils, thick airfoil at the root (around 16%) and thinner toward the tip (around 8%), sweep angle around 35°, root airfoil with prolonged chord in order to accommodate the main landing gears and some 5° of dihedral.
For other wing layouts, any book about preliminary airplane design contains the relevant general guidelines.


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Cruising at the speed of sound
Is it possible or feasible for an aircraft to continuously cruise at the speed of sound? Is the drag at this point higher or lower than in the high Mach 0.98 or Mach 1-1.2 region?

As shown in the following plot (from this answer), the F16 has a drag coefficient which doubles at transonic speeds but then remains basically constant past Mach 1.

So an F16 could definitely do it. And for a more modern aircraft, the rise in drag would even be more contained.

I'd like to see that plot for an F-22 or other fighter that can cruise supersonically without reheat for comparison.  Not sure if the F22 needs reheat to get there, then can cruise at military power, or if it can go moderately supersonic with military power alone.

@JohnK: I'd also like to see that... and obviously the one of the Concorde  For a supercruiser (like the Concorde) I'd expect only a peak in the drag coefficient at transonic speeds. Afterwards the coefficient should be just a bit higher than at subsonic speed.

@JohnK the Super Tomcat would also have been able to supercruise.